Conventional lubrication systems for lubricating the spline connections and support bearings in transmissions, winches, etc., are frequently complex in that they use pumps, regulators, and sophisticated distribution networks. Such systems are costly to manufacture and substantially increase the initial and operating expenses by requiring additional parts and by absorbing part of the otherwise utilizable horsepower of the vehicle or machine with which the transmission, winch, etc., is used. A lubrication system overcoming many of these disadvantages is found in U.S. Pat. No. 3,785,458, assigned to the assignee of this application. However, this system which utilizes an axially disposed conducting tube is not suitable for use with a pair of axially connected shafts due to the requirement of having access to the end of the shaft on the shaft axis. Also, this system is not suitable for use with even a single spline-connected shaft where axial access to its ends is restricted for some reason.
While it would be possible to merely have a lubricant drain hole in the wall of a collar spline connecting a pair of axially aligned shafts, such systems would be unsatisfactory for various reasons.
First of all, depending on the orientation of the drain hole when the shaft stops, all of the lubricant contained in the chamber formed between the shaft ends and the joining collar might be drained out. This would result in unlubricated spline couplings for a short period after shaft rotation is commenced and would produce undesirable fretting in the splined shafts.
Secondly, the lubricant level in the chamber would be variable and would tend to either over-lubricate or under-lubricate the splines.